Problem: $\dfrac{4}{6} - \dfrac{1}{2} = {?}$
$ = {\dfrac{4 \times 1}{6 \times 1}} - {\dfrac{1 \times 3}{2 \times 3}} $ $ = {\dfrac{4}{6}} - {\dfrac{3}{6}} $ $ = \dfrac{{4} - {3}}{6} $ $ = \dfrac{1}{6}$